January: IMS Board

For what applications are copper IMS most suitable?

Copper IMS are deployed in many automotive- and industrial aplications with higher power losses and/or currents. Besides high-power LED applications DC/CD converters and motor applications are preferred application fields. Based on the lower cost copper IMS are also utilized as a replacement for DCBs.

What's the meaning of IMS?

The abbreviation IMS stands for "Insulated Metal Substrate". Products utilising IMS technology are built up of a copper or aluminium back side metal sheet as a basis and one or more laminated copper- and base material layers. The IMS technology is very efficient for higher power applications featuring high power losses at limited layout density. Application examples are power-LED modules, DC/DC converters and motor control boards.

Microsection view of a thermosimulation of an IMS Board

Why is SCHWEIZER manufacturing copper IMS and no aluminum IMS?

Unprotected aluminium substrates must not pass wet chemical PCB process steps due to bath contamination. Processing aluminium substrates does not match with highly automated PCB processes, which are part of SCHWEIZER's formula for success. Therefore SCHWEIZER is focussing on IMS technologies based on 1 mm copper substrates, other thicknesses on request. The material characteristics of copper offer many advantages in terms of thermal and electrical behaviour compared to aluminium. Furthermore the thermal expansion coefficient of copper (17 ppm/K) compared to aluminium (24 ppm/K) is advantageous especially to support highly reliable solder connections between the PCB and modern power LED packages based on aluminium nitride and sapphire substrates.

How many layers can be built up on the basis of a copper IMS substrate?

Depending on the complexity of the circuitry SCHWEIZER is offering up to four electrical layers. The copper substrate does not count as electrical layer.

Do I have to use a thermal interface material (TIM) to assure a sufficient heat transfer from the IMS to the heatsink?

TIMs are thermally highly conductive materials which are e.g. employed to improve the heat transfer from the PCB to the heat sink. When deciding whether to use a TIM in the application or not, the engineer may consider that direct mounting of IMS onto the heatsink is a cost efficient alternative. In many cases the thermal performance of direct mounted IMS is comparable. Besides the thermal resistance of the TIM itself based on material thickness and specific thermal conductivity also thermal resistances of interfaces have to be considered.